My invention pertains to a method and apparatus for determining and positioning a cant in relation to edging saws or cutters, chippers, or band saws to optimize the yield from the cant.
In the lumber industry it has been common practice to control the position of a cant on a slat bed conveyor feeding edging saws by visual evaluation of an operator, after which the cant is fed into the edging saws. This practice results in low yield from the cant or boards with excessive wane resulting in scrap. Production rate is controlled by the ability of the operator to judge and set the cant relative to the edging saws.
Sorenson U.S. Pat. No. 2,111,699 discloses the use of mechanical fingers to determine cant edge contour and direct positioning of the cant on the conveyor feeding edging saws. Barr et al U.S. Pat. No. 3,931,501 discloses photoelectric cell sensors for surface defect detection by passing the detectors longitudinally over the work piece lengths.
The manual positioning of the cant in relation to the edging saws is slow and tedious and subject to operator mistakes. The mechanical determination of the edge contour does not provide for determination of the maximum yield that can be obtained from a given cant. It is the general object of the present invention to provide a method and apparatus which will achieve the purpose of determining the maximum useable material from a cant and directing the positioning of that cant in relation to edging saws.
Another object of this invention is the provision of equipment that will determine maximum cant yield at a high rate of speed.
Another object of this invention is to provide for edge sensing that is not affected by color.
Another object of this invention is to provide cant edge sensing that is not affected by normal vibration, dust and dirt.
Another object of this invention is to provide cant edge sensing units requiring a minimum of space.
Another object of this invention is to provide cant edge sensors that are accurate independent of the cant surface that faces upwardly.
Another object of this invention is to provide cant edge sensors that will sense the surface edge of center cants.
Another object of this invention is to determine the maximum production from a given cant and position the cant in relation to edging saws to yield that production.
Another object of this invention is the provision of equipment that is highly accurate.
Broadly considered the foregoing and other objects of this invention are accomplished by a method which comprises positioning a plurality of proximity sensors relative to the surface of a cant, conveying the cant past the sensors encoding a series of pulses into a computer during the time the cant is passing the sensors, determining the position to set the cant relative to edging saws to optimize cant yield, directing a pair of positioning heads to position the cant in relation to the edging saws and transferring the cant to a longitudinal conveyor for feeding the edging saws.
The objects of the invention are further achieved by providing an apparatus for accomplishing the foregoing functions.